Two atom bridged dicarbonate compounds as internal donors in catalysts for polypropylene manufacture

ABSTRACT

A compound suitable for use as an internal electron donor having a structure: 
     
       
         
         
             
             
         
       
         
         
           
             wherein R 1  is independently at each occurrence, an aliphatic or aromatic hydrocarbon, or substituted hydrocarbon group containing from 1 to 20 carbon atoms; R 2  is independently at each occurrence, a hydrogen atom or aliphatic or aromatic hydrocarbon, or substituted hydrocarbon group containing from 1 to 20 carbon atoms; and R3 is an aliphatic hydrocarbyl group having 1 to 3 carbon atoms.

This application is a non-provisional application claiming priority fromthe U.S. Provisional Patent Application No. 61/265,931, filed on Dec. 2,2009, and also from the U.S. National Utility application Ser. No.12/956,050, filed on Nov. 30, 2010, entitled “TWO ATOM BRIDGEDDICARBONATE COMPOUNDS AS INTERNAL DONORS IN CATALYSTS FOR POLYPROPYLENEMANUFACTURE,” the teachings of which are incorporated by referenceherein, as if reproduced in full hereinbelow.

This invention relates to components useful in propylene polymerizationcatalysts, and particularly relates to electron donor components used incombination with magnesium-containing supported titanium-containingcatalyst components.

BACKGROUND AND SUMMARY OF THE INVENTION

Use of solid, transition metal-based, olefin polymerization catalystcomponents is well known in the art including such solid componentssupported on a metal oxide, halide or other salt such aswidely-described magnesium-containing, titanium halide-based catalystcomponents. Such catalyst components are commonly referred to as“supported”. Although many polymerization and copolymerization processesand catalyst systems have been described for polymerizing orcopolymerizing alpha-olefins, it is advantageous to tailor a process andcatalyst system to obtain a specific set of properties of a resultingpolymer or copolymer product. For example, in certain applications, acombination of acceptably high activity, good morphology, desiredparticle size distribution, acceptable bulk density, and the like arerequired together with polymer characteristics such asstereospecificity, molecular weight distribution, and the like.

Typically, supported catalyst components useful for polymerizingpropylene and higher alpha-olefins, as well as for polymerizingpropylene and higher olefins with minor amounts of ethylene and otheralpha-olefins contain an internal electron donor component. Suchinternal electron donor is an integral part of the solid supportedcatalyst component and is distinguished from an external electron donorcomponent, which together with an aluminum alkyl component, typicallycomprises the catalyst system. While the internal electron donor is anintegral part of the solid supported component, the external electrondonor may be combined with the solid supported component shortly beforethe combination is contacted with an olefin monomer or in the presenceof olefin monomer. The external electron donor is commonly referred toas a selectivity control agent (or “SCA”), and the supported catalystcomponent is commonly referred to as a procatalyst.

Selection of the internal electron donor can affect catalyst performanceand the resulting polymer formed from a catalyst system. Generally,organic electron donors have been described as useful in preparation ofthe stereospecific supported catalyst components including organiccompounds containing oxygen, nitrogen, sulfur, and/or phosphorus. Suchcompounds include organic acids, organic acid anhydrides, organic acidesters, alcohols, ethers, aldehydes, ketones, amines, amine oxides,amides, thiols, various phosphorus acid esters and amides, and the like.Mixtures of organic electron donors have been described as useful whenincorporated into supported catalyst components. Examples of organicelectron donors include dicarboxy esters such as alkyl phthalate andsuccinate esters.

In current practice, alkyl phthalate esters are commonly used asinternal electron donors in commercial propylene polymerization catalystsystems. However, certain environmental questions have been raisedconcerning continued use of phthalate derivatives in applications wherehuman contact is anticipated.

Particular uses of propylene polymers depend upon the physicalproperties of the polymer, such as molecular weight, viscosity,stiffness, flexural modulus, and polydispersity index (molecular weightdistribution (Mw/Mn)). In addition, polymer or copolymer morphologyoften is critical and typically depends upon catalyst morphology. Goodpolymer morphology generally involves uniformity of particle size andshape, resistance to attrition and an acceptably high bulk density.Minimization of very small particles (fines) typically is importantespecially in gas-phase polymerizations or copolymerizations in order toavoid transfer or recycle line pluggage.

The art presently recognizes a finite set of compounds suitable for useas internal electron donors in supported catalyst components. With thecontinued diversification and sophistication of applications forolefin-based polymers, the art recognizes the need for olefin-basedpolymers with improved and varied properties. Desirable would beinternal electron donors in supported catalyst components thatcontribute to strong catalyst activity and high hydrogen response duringpolymerization. Further desired are internal electron donors insupported catalyst components that produce propylene-based polymers withhigh isotacticity, commonly expressed as a xylenes soluble fraction (XS)and/or final melting temperatue (TMF).

The invention described relates to use of an internal modifier (internalelectron donor) in a propylene polymerization catalyst component, whichcontains at least two carbonate functionalities.

Accordingly, one embodiment of the invention is a solid,hydrocarbon-insoluble, catalyst component useful in polymerizingolefins, said catalyst component containing magnesium, titanium, andhalogen, and further containing an internal electron donor comprising acompound having a structure:

[R₁—O—C(O)—O—]_(x)R₂

wherein R₁ is independently at each occurrence, an aliphatic or aromatichydrocarbon, or substituted hydrocarbon group containing from 1 to 20carbon atoms; x is 2-4; and R₂ is an aliphatic or aromatic hydrocarbon,or substituted hydrocarbon group containing from 1 to 20 carbon atoms,provided that there are 2 atoms in the shortest chain connecting a firstR₁—O—C(O)—O— group and a second R₁—O—C(O)—O— group.

DETAILED DESCRIPTION OF THE INVENTION Definitions

All references to the Periodic Table of the Elements herein shall referto the Periodic Table of the Elements, published and copyrighted by CRCPress, Inc., 2003. Also, any references to a Group or Groups shall be tothe Groups or Groups reflected in this Periodic Table of the Elementsusing the IUPAC system for numbering groups. Unless stated to thecontrary, implicit from the context, or customary in the art, all partsand percents are based on weight. For purposes of United States patentpractice, the contents of any patent, patent application, or publicationreferenced herein are hereby incorporated by reference in their entirety(or the equivalent US version thereof is so incorporated by reference),especially with respect to the disclosure of synthetic techniques,definitions (to the extent not inconsistent with any definitionsprovided herein) and general knowledge in the art.

The term “comprising,” and derivatives thereof, is not intended toexclude the presence of any additional component, step or procedure,whether or not the same is disclosed herein. In order to avoid anydoubt, all compositions claimed herein through use of the term“comprising” may include any additional additive, adjuvant, or compoundwhether polymeric or otherwise, unless stated to the contrary. Incontrast, the term, “consisting essentially of” excludes from the scopeof any succeeding recitation any other component, step or procedure,excepting those that are not essential to operability. The term“consisting of” excludes any component, step or procedure notspecifically delineated or listed. The term “or”, unless statedotherwise, refers to the listed members individually as well as in anycombination.

Any numerical range recited herein, includes all values from the lowervalue to the upper value, in increments of one unit, provided that thereis a separation of at least 2 units between any lower value and anyhigher value. As an example, if it is stated that the amount of acomponent, or a value of a compositional or a physical property, suchas, for example, amount of a blend component, softening temperature,melt index, etc., is between 1 and 100, it is intended that allindividual values, such as, 1, 2, 3, etc., and all subranges, such as, 1to 20, 55 to 70, 197 to 100, etc., are expressly enumerated in thisspecification. For values which are less than one, one unit isconsidered to be 0.0001, 0.001, 0.01 or 0.1, as appropriate. These areonly examples of what is specifically intended, and all possiblecombinations of numerical values between the lowest value and thehighest value enumerated, are to be considered to be expressly stated inthis application. In other words, any numerical range recited hereinincludes any value or subrange within the stated range. Numerical rangeshave been recited, as discussed herein, reference melt index, melt flowrate, and other properties.

The term “composition,” as used herein, includes a mixture of materialswhich comprise the composition, as well as reaction products anddecomposition products formed from the materials of the composition.

The terms “blend” or “polymer blend,” as used herein, is a blend of twoor more polymers. Such a blend may or may not be miscible (not phaseseparated at molecular level). Such a blend may or may not be phaseseparated. Such a blend may or may not contain one or more domainconfigurations, as determined from transmission electron spectroscopy,light scattering, x-ray scattering, and other methods known in the art.

The term “polymer” is a macromolecular compound prepared by polymerizingmonomers of the same or different type. “Polymer” includes homopolymers,copolymers, terpolymers, interpolymers, and so on. The term“interpolymer” means a polymer prepared by the polymerization of atleast two types of monomers or comonomers. It includes, but is notlimited to, copolymers (which usually refers to polymers prepared fromtwo different types of monomers or comonomers, terpolymers,tetrapolymers, and the like.

The term “interpolymer,” as used herein, refers to polymers prepared bythe polymerization of at least two different types of monomers. Thegeneric term interpolymer thus includes copolymers, usually employed torefer to polymers prepared from two different monomers, and polymersprepared from more than two different types of monomers.

The term “olefin-based polymer” is a polymer containing, in polymerizedform, a majority weight percent of an olefin, for example ethylene orpropylene, based on the total weight of the polymer. Nonlimitingexamples of olefin-based polymers include ethylene-based polymers andpropylene-based polymers.

The term, “ethylene-based polymer,” as used herein, refers to a polymerthat comprises a majority weight percent polymerized ethylene monomer(based on the total weight of polymerizable monomers), and optionallymay comprise at least one polymerized comonomer.

The term, “propylene-based polymer,” as used herein, refers to a polymerthat comprises a majority weight percent polymerized propylene monomer(based on the total amount of polymerizable monomers), and optionallymay comprise at least one polymerized comonomer.

As used herein, the term “hydrocarbyl” and “hydrocarbon” refer tosubstituents containing only hydrogen and carbon atoms, includingbranched or unbranched, saturated or unsaturated, cyclic, polycyclic,fused, or acyclic species, and combinations thereof. Nonlimitingexamples of hydrocarbyl groups include alkyl-, cycloalkyl-, alkenyl-,alkadienyl-, cycloalkenyl-, cycloalkadienyl-, aryl-, aralkyl, alkylaryl,and alkynyl- groups. As used herein, the terms “substituted hydrocarbyl”and “substituted hydrocarbon” refer to a hydrocarbyl group that issubstituted with one or more nonhydrocarbyl substituent groups. Anonlimiting example of a nonhydrocarbyl substituent group is aheteroatom. As used herein, a “heteroatom” refers to an atom other thancarbon or hydrogen. The heteroatom can be a non-carbon atom from GroupsIV, V, VI, and VII of the Periodic Table. Nonlimiting examples ofheteroatoms include: halogens (F Cl, Br, I), N, O, P, B, S, and Si. Asubstituted hydrocarbyl group also includes a halohydrocarbyl group anda silicon-containing hydrocarbyl group. As used herein, the term“halohydrocarbyl” group refers to a hydrocarbyl group that issubstituted with one or more halogen atoms.

The term “alkyl,” as used herein, refers to a branched or unbranched,saturated or unsaturated acyclic hydrocarbon radical. Nonlimitingexamples of suitable alkyl radicals include, for example, methyl, ethyl,n-propyl, i-propyl, 2-propenyl (or allyl), vinyl, n-butyl, t-butyl,i-butyl (or 2-methylpropyl), etc. The alkyls have 1 to 20 carbon atoms.

The term “substituted alkyl,” as used herein, refers to an alkyl as justdescribed in which one or more hydrogen atom bound to any carbon of thealkyl is replaced by another group such as a halogen, aryl, substitutedaryl, cycloalkyl, substituted cycloalkyl, heterocycloalkyl, substitutedheterocycloalkyl, halogen, haloalkyl, hydroxy, amino, phosphido, alkoxy,amino, thio, nitro, other heteroatom containing groups, and combinationsthereof. Suitable substituted alkyls include, for example, benzyl,trifluoromethyl and the like.

The term “aryl,” as used herein, refers to an aromatic substituent whichmay be a single aromatic ring or multiple aromatic rings which are fusedtogether, linked covalently, or linked to a common group such as amethylene or ethylene moiety. The aromatic ring(s) may include phenyl,naphthyl, anthracenyl, and biphenyl, among others. The aryls have 6 to20 carbon atoms.

The term “carbonate” as used herein, refers to a functional group withina larger molecule that contains a carbon atom bound to three oxygenatoms, one of which is double bonded. Such compounds are also known asorganocarbonates or carbonate esters.

The supported catalyst components of this invention contain at least oneinternal electron donor comprising electron donating substituentscomprising a dicarbonate. Dicarbonates are defined as those compoundscorresponding to the following structure:

[R₁—O—C(O)—O—]_(x)R₂

wherein R₁ is independently at each occurrence, an aliphatic or aromatichydrocarbon, or substituted hydrocarbon group containing from 1 to 20carbon atoms; x is 2-4; and R₂ is an aliphatic or aromatic hydrocarbon,or substituted hydrocarbon group containing from 1 to 20 carbon atoms,provided that there are 2 atoms in the shortest chain connecting a firstR₁—O—C(O)—O— group and a second R₁—O—C(O)—O— group.

It is preferred that x be equal to 2, and as a result, in the broadestsense of the invention the term “dicarbonate” is used to genericallydescribe these compounds even though compounds with 3 or even 4carbonate groups are contemplated.

For many applications it is preferred that the R₁ group be an aliphaticor aromatic hydrocarbon group. It is also preferred that such aliphaticgroup be of relatively shorter length, for example from 1-6 carbonatoms, and such aromatic group be relatively compact, for example havingfrom 6-10 carbon atoms

The R₂ groups in the dicarbonates useful in the present invention aresuch that there are 2 atoms in the shortest chain between 2 carbonategroups. Preferably, these linking atoms are carbon atoms but heteroatomssuch as oxygen, nitrogen, silicon, or phosphorous may also be used. Itshould be understood that the 2 linking atoms refers only to the atomsin the shortest chain between the carbonate groups and that the R₂groups are typically much larger, as they contain atoms which do notdirectly link the carbonate groups. Preferred R₂ groups include phenylswhere the linking atoms are adjacent on the ring, and naphthalenes,where the linking atoms are adjacent on one of the fused rings. Suchphenyls or naphthalenes may advantageously contain alkyl groups or othersubstituents.

The hydrocarbons useful in the present invention may be substituted withatoms other than carbon or hydrogen. For example, alkyl groups used inthis invention may be substituted with compatible groups containingheteroatoms including nitrogen, oxygen, phosphorus, silicon, andhalogens. Thus, a hydrocarbon group used in this invention may besubstituted with an ether, amine, amide, chloro, bromo, or silyl group,for example. Similarly, cyclic structures which may be incorporated intothe donor compounds as part of either the R₁ or R₂ groups may containhetero atoms, such as nitrogen, oxygen, silicon, and phosphorus.

Non-limiting examples of some specific dicarbonates for use in thepresent invention include the following, and their substitutedderivatives

The dicarbonate materials suitable for use as internal electron donorsin the present invention can be made according to methods known in theart. One suitable method for making a true dicarbonate (that is, wherex=2) involves reacting a diol with at least two molar equivalents of asubstituted cholorformate. Thus the reaction could be described as:

R₂(OH)₂+2Cl—C(O)—OR₁→[R₁—O—C(O)—O—]₂R₂

where R₁ and R₂ are as described above. A suitable base may be presentto sequester the hydrochloric acid liberated during the reaction. Asuitable variation of this method is to first react the diol with asuitable base to effect partial or complete deprotonation, followed bytreatment with at least 2 molar equivalents of a substitutedcholorformate.

The dicarbonates of the present invention are useful as internalelectron donors in high activity supported titanium-containingZiegler-Natta catalysts commonly used in the manufacture ofpolypropylene.

Supported titanium-containing components useful in this inventiongenerally are supported on hydrocarbon-insoluble, magnesium-containingcompounds in combination with an electron donor compound. Such supportedtitanium-containing olefin polymerization catalyst component typicallyis formed by reacting a titanium (IV) halide, an organic electron donorcompound and a magnesium-containing compound. Optionally, such supportedtitanium-containing reaction product may be further treated or modifiedby further chemical treatment with additional electron donor or Lewisacid species. The resulting supported titanium-containing components arealso referred to as “supported catalyst components” or “procatalysts.”

Suitable magnesium-containing compounds include magnesium halides; areaction product of a magnesium halide such as magnesium chloride ormagnesium bromide with an organic compound, such as an alcohol or anorganic acid ester, or with an organometallic compound of metals ofGroups I-III; magnesium alcoholates; mixed magnesium/titanium halidealcoholates; or magnesium alkyls.

Examples of supported catalyst components are prepared by reacting amagnesium chloride, alkoxy magnesium chloride or aryloxy magnesiumchloride, or mixed magnesium/titanium halide alcoholate with a titaniumhalide, such as titanium tetrachloride, and further incorporation of anelectron donor compound. In a preferable preparation, themagnesium-containing compound is dissolved, or is in a slurry, in acompatible liquid medium, such as a hydrocarbon or halogenatedhydrocarbon to produce suitable catalyst component particles.

The possible supported solid catalyst components listed above are onlyillustrative of many possible solid, magnesium-containing, titaniumhalide-based, hydrocarbon-insoluble catalyst components useful in thisinvention and known to the art. This invention is not limited to aspecific supported catalyst component.

Supported catalyst components known to the art may be used with theinternal donors described in this invention. Typically, the internalelectron donor material of this invention is incorporated into a solid,supported catalyst component during formation of such component.Typically, such electron donor material is added with, or in a separatestep, during treatment of a solid magnesium-containing material with asuitable titanium source, such as a titanium (IV) compound. Suchmagnesium-containing material typically is in the form of discreteparticles and may contain other materials such as transition metals andorganic compounds. Also, a mixture of magnesium chloride, titaniumtetrachloride and the internal donor may be formed into a supportedcatalyst component by ball-milling.

Magnesium Source

The magnesium source is preferably in the form of a supported catalystcomponent precursor prepared in accordance with any of the proceduresdescribed in, for example, U.S. Pat. Nos. 4,540,679; 4,612,299;4,866,022; 4,946,816; 5,034,361; 5,066,737; 5,082,907; 5,106,806;5,146,028; 5,151,399; 5,229,342 and 7,491,781, the disclosures of whichare incorporated by reference herein in their entirety. The magnesiumsource may also be a magnesium halide, alkyl, aryl, alkaryl, alkoxide,alkaryloxide or aryloxide, alcohol aducts thereof, carbonatedderivatives thereof, or sulfonated derivatives thereof, but preferablyis an alcohol adduct of a magnesium halide, a magnesium dialkoxide, acarbonated magnesium dialkoxide, a carbonated magnesium diaryloxide, ora mixed magnesium/titanium halide alcoholate. Magnesium compoundscontaining one alkoxide and one aryloxide group can also be employed, aswell as magnesium compounds containing a halogen in addition to onealkoxide, alkaryloxide, or aryloxide group. The alkoxide groups, whenpresent, most suitable contain from 1 to 8 carbons, preferably from 2 to6 carbon atoms. The aryloxide groups, when present, most suitablecontain from 6 to 10 carbons. When a halogen is present, it ispreferably chlorine.

Among the magnesium dialkoxides and diaryloxides which can be employedare those of the formula Mg(OC(O)OR³)_(a)(OR⁴)_(2-a) wherein R³ and R⁴are alkyl, alkaryl, or aryl groups, and a is about 0.1 to about 2. Themost preferable magnesium compound contaning a carbonate group iscarbonated magnesium diethoxide (CMEO), Mg(OC(O)OEt)₂. Optionally themagnesium may be halogenated with an additional halogenating agent,e.g., thionyl chloride or alkylchlorosilanes, prior to contact with thetetravalent titanium source.

A somewhat different type of magnesium source is described by thegeneral formula Mg₄(OR⁵)₆(R⁶OH)₁₀A in which each R⁵ or R⁶ is a loweralkyl of up to 4 carbon atoms inclusive and A is one or more anionshaving a total charge of −2. The manufacturing of this magnesium sourceis disclosed in U.S. Pat. No. 4,710,482 to Job which is incorporatedherein by reference.

Another particularly preferred magnesium source is one that containsmoieties magnesium and titanium and probably moieties of at least someof halide, alkoxide, and a phenolic compound. Such complex procatalystprecursors are produced by contacting a magnesium alkoxide, a titaniumalkoxide, a titanium halide, a phenolic compound, and an alkanol. SeeU.S. Pat. No. 5,077,357 to Job which is incorporated herein byreference.

A further useful magnesium source is a mixed magnesium/titanium compound(“MagTi”). The “MagTi precursor” has the formula Mg_(b)Ti(OR⁷)_(c)X¹_(d) wherein R⁷ is an aliphatic or aromatic hydrocarbon radical having 1to 14 carbon atoms or COR⁸ wherein R⁸ is an aliphatic or aromatichydrocarbon radical having 1 to 14 carbon atoms; each OR⁷ group is thesame or different; X¹ is independently chlorine, bromine or iodine,preferably chlorine; b is 0.5 to 56, or 2 to 4; c is 2 to 116 or 5 to15; and d is 0.5 to 116, or 1 to 3. These precursors are prepared bycontrolled precipitation through removal of an alcohol from the reactionmixture used in their preparation. As such, a reaction medium comprisesa mixture of an aromatic liquid, especially a chlorinated aromaticcompound, most especially chlorobenzene, with an alkanol, especiallyethanol. Suitable halogenating agents include titanium tetrabromide,titanium tetrachloride or titanium trichloride, especially titaniumtetrachloride. Removal of the alkanol from the solution used in thehalogenation, results in precipitation of the solid precursor, havingespecially desirable morphology and surface area. Moreover, theresulting precursors are particularly uniform in particle size.

An additional useful magnesium source is a benzoate-containing magnesiumchloride material (“BenMag”). As used herein, a “benzoate-containingmagnesium chloride” (“BenMag”) can be a supported catalyst component(i.e., a halogenated supported catalyst component precursor) whichcontains a benzoate internal electron donor. The BenMag material mayalso include a titanium moiety, such as a titanium halide. The benzoateinternal donor is labile and can be replaced by other electron donorsduring the supported catalyst component and/or catalyst synthesis.Nonlimiting examples of suitable benzoate groups include ethyl benzoate,methyl benzoate, ethyl p-methoxybenzoate, methyl p-ethoxybenzoate, ethylp-ethoxybenzoate, ethyl p-chlorobenzoate. A preferred benzoate group isethyl benzoate. Nonlimiting examples of suitable BenMag procatalystprecursors include catalysts of the trade names SHAC™ 103 and SHAC™ 310available from The Dow Chemical Company, Midland, Mich. The BenMagsupported catalyst component precursor may be a product of halogenationof a supported catalyst component precursor (e.g., a magnesiumdialkoxide, a carbonated magnesium dialkoxide, or a MagTi precursor) inthe presence of a benzoate compound.

Titanium Source

The titanium source for the supported catalyst component preferably is atetravalent titanium which contains at least two halogen atoms, andpreferably contains four halogen atoms, e.g., Ti(OR⁹¹)_(c)X² _(4-e),wherein R⁹ is a hydrocarbon, and X² is a halide and e is 0 to 2. Mostpreferably these halogen atoms are chlorine atoms. Titanium compoundscontaining up to two alkoxy, alkaryloxy or aryloxy groups can beemployed. The alkoxy groups, when present, most suitably contain from 1to 8 carbon atoms, preferably 2 to 6 carbon atoms. The aryloxy oralkaryloxy groups, when present, most suitably contain from 6 to 12carbon atoms, preferably from 6 to 10 carbon atoms. Examples of suitablealkoxy- and aryloxy-titanium halides include diethoxy titaniumdibromide, isopropoxy titanium triiodide, dihexoxy titanium dichloride,and phenoxy titanium trichloride. The most preferable titanium source isTiCl₄.

Supported Catalyst Component Manufacture

The magnesium compound preferably is reacted (i.e., halogenated) withthe tetravalent titanium halide in the presence of an internal electrondonor and optionally a halohydrocarbon. Optionally, an inert hydrocarbondiluent or solvent also may be present. Various methods for preparingsupported catalyst components are known in the art. Some of thesemethods are described in, for example, U.S. Pat. Nos. 4,442,276;4,460,701; 4,547,476; 4,816,433; 4,829,037; 4,927,797; 4,990,479;5,066,738; 5,028,671; 5,153,158; 5,247,031 and 5,247,032. Regardless ofthe method of formation, the supported catalyst components of thisinvention include the internal electron donor material described in thisinvention.

When optionally employed, the halohydrocarbon used may be aromatic,aliphatic, or alicyclic. Most preferably, the halogen of thehalohydrocarbon is chlorine. Aromatic halohydrocarbons are preferred,particularly those containing from 6 to 12 carbon atoms, preferably 6 to10 carbon atoms. Preferably such halohydrocarbons contain 1 or 2 halogenatoms, although more may be present if desired. Suitable aromatichalohydrocarbons include, but are not limited to chlorobenzene,bromobenzene, dichlorobenzene, dichlorodibromobenzene, chlorotoluene,dichlorotoluene, and chloronaphthalene. The aliphatic halohydrocarbonscontain from 1 to 12 carbon atoms, preferably from 1 to 9 carbon atomsand at least 2 halogen atoms. Suitable aliphatic halohydrocarbonsinclude, but are not limited to dibromomethane, trichloromethane,1,2-dichloroethane, trichloroethane, dichlorofluoroethane,hexachloroethane, trichloropropane, chlorobutane, dichlorobutane,chloropentane, trichlorofluorooctane, tetrachloroisooctane,dibromodifluorodecane, carbon tetrachloride, and trichloroethane. Thealicyclic halohydrocarbons which can be employed contain from 3 to 12carbon atoms, and preferably from 3 to 9 carbon atoms, and at least 2halogen atoms. Suitable alicyclic halohydrocarbons includedibromocyclobutane, and trichlorocyclohexane.

The optional inert hydrocarbon diluent may be aliphatic, aromatic oralicyclic. Some exemplary diluents are isopentane, n-octane, isooctane,xylene, or toluene.

Halogenation of the magnesium compound with the halogenated tetravalenttitanium halide is effected employing an excess of the titanium halide.At least 2 moles of the titanium halide should be employed per mole ofthe magnesium compound. Preferably from about 4 moles to about 100 molesof the titanium halide are employed per mole of the magnesium compound,and most preferably from about 4 moles to about 20 moles of the titaniumhalide are employed per mole of the magnesium compound.

When optionally employed, the halohydrocarbon is used in an amountsufficient to dissolve the titanium halide and the internal electrondonor, and to adequately disperse the magnesium compound. Usually thedispersion contains from about 0.005 to about 2.0 moles of the solidmagnesium compound per mole of halohydrocarbon, preferably from about0.01 to about 1.0 mole of the solid magnesium compound per mole of thehalohydrocarbon. The internal electron donor is employed in an amountsufficient to provide a molar ratio of said compound to the titaniumhalide of from about 0.0005:1 to about 2.0:1, preferably from about0.001:1 to about 0.1:1. About 1:100 to 100:1 by volume ofhalohydrocarbon to optional diluent may be used.

Halogenation can be effected at a temperature up to about 150° C.,preferably from about 80° C. to about 140° C. Usually the reaction isallowed to proceed over a period of 0.1 to 6 hours, preferably betweenabout 0.5 to about 3.5 hours. For convenience, halogenation is usuallyeffected at atmospheric pressure, although a range of pressures can beemployed, e.g., 0.5 atm (50,700 Pa) to 5 atm (507,000 Pa). Thehalogenated product, like the starting magnesium compound, is a solidmaterial which can be isolated from the liquid reaction medium bydrying, filtration, decantation, evaporation, distillation or anysuitable method.

After separation, the halogenated product (also termed the supportedcatalyst component upon halogenation) may be treated one or more timeswith additional tetravalent titanium halide to remove residual alkoxyand/or aryloxy groups and maximize catalyst activity or other desiredproperties. Preferably, the halogenated product is treated at leasttwice with separate portions of the tetravalent titanium halide.Generally, the reaction conditions employed to treat the halogenatedproduct with the titanium halide are the same or similar to thoseemployed during the initial halogenation of the magnesium compound, andthe internal electron donor may or may not be present during thetreatment(s). When optionally employed, the halohydrocarbon is typicallyused to dissolve the titanium halide and disperse the solid, halogenatedproduct. If desired, the halogenated product may be treated with theacid halide before or after it is treated with the titanium compound forthe second time. From 5 mmol to 200 mmol of the acid halide generallyare employed per mole of magnesium in the halogenated product (i.e.supported catalyst component). Suitable acid halides include benzoylchloride, phthaloyl dichloride, 2,3-naphthalenedicarboxylic aciddichloride, endo-5-norbornene-2,3-dicarboxylic acid dichloride, maleicacid dichloride, citraconic acid dichloride, and the like. A usefulprocedure for treatment of the halogentated product by acid halides isdescribed in U.S. Pat. No. 6,825,146.

After the supported catalyst component has been treated one or moretimes with additional tetravalent titanium halide, it is separated fromthe liquid reaction medium, and preferably washed with an inerthydrocarbon such as isopentane, isooctane, isohexane, hexane, pentane,heptane, or octane to remove unreacted titanium compounds or otherimporities. The supported catalyst component can then be dried, or itmay slurried in a hydrocarbon, especially a relatively heavy hydrocarbonsuch as mineral oil for further storage or use. If dried, the dryingprocess may be by filtration, evaporation, heating or other methodsknown in the art.

Not wishing to be bound by any particular theory, it is believed that(1) further halogenation by contacting the previously formed supportedcatalyst component with a titanium halide compound, especially asolution thereof in a halohydrocarbon diluent, and/or (2) furtherwashing the previously formed supported catalyst component with ahalohydrocarbon at an elevated temperature (100° C. to 150° C.), resultsin desirable modification of the supported catalyst component, possiblyby removal of certain inactive metal compounds that are soluble in theforegoing diluent. Accordingly, the supported catalyst component may becontacted with a halogenating agent, such as a mixture of a titaniumhalide and a halohydrocarbon diluent, such as TiCl₄ and chlorobenzene,one or more times prior to isolation or recovery. Correspondingly, thesupported catalyst component may be washed at a temperature between 100°C. to 150° C. with a halohydrocarbon such as chlorobenzene oro-chlorotoluene one or more times prior to isolation or recovery.

The final supported catalyst component product suitably has a titaniumcontent of from about 0.5 percent by weight to about 6.0 percent byweight, or from about 1.0 percent by weight to about 5.0 percent byweight. The weight ratio of titanium to magnesium in the solid supportedcatalyst component is suitably between about 1:3 and about 1:160, orbetween about 1:4 and about 1:50, or between about 1:6 and 1:30. Theinternal electron donor is present in the supported catalyst componentin a molar ratio of internal electron donor to magnesium of from about0.001:1 to about 10.0:1, or from about 0.01:1 to about 0.4:1. Weightpercent is based on the total weight of the supported catalystcomposition.

The internal electron donor material useful in this invention may becombined with additional internal electron donors such as ethers,esters, amines, imines, nitriles, phosphines, stibines, arsines,polyhydrocarbyl phosphonates, phosphinates, dialkylphthalates,phosphates or phosphine oxides, or alkyl aralkylphthalates, wherein thealkyl moiety contains from 1 to 10, preferably 2 to 6, carbon atoms andthe aralkyl moiety contains from 7 to 10, preferably to 7 to 8, carbonatoms, or an alkyl ester of an aromatic monocarboxylic acid wherein themonocarboxylic acid moiety contains from 6 to 10 carbon atoms and thealkyl moiety contains from 1 to 6 carbon atoms. Such combination orincorporation of additional internal electron donors may occur in any ofthe steps employing the titanium compound.

Prepolymerization or encapsulation of the catalyst or supported catalystcomponent of this invention also may be carried out prior to being usedin the polymerization or copolymerization of alpha olefins. Aparticularly useful prepolymerization procedure is described in U.S.Pat. No. 4,579,836, which is incorporated herein by reference.

Catalyst

The olefin polymerization catalyst (or “catalyst composition”) includesthe above-described supported catalyst component, a cocatalyst, andoptionally a selectivity control agent (also know as an “SCA”, “externaldonor”, or “external electron donor”), and optionally an activitylimiting agent (or “ALA”).

Cocatalyst

The cocatalyst may be chosen from any of the known activators of olefinpolymerization catalyst systems, but organoaluminum compounds arepreferred. Such cocatalysts can be employed individually or incombinations thereof. Suitable organoaluminum cocatalysts have theformula Al(R¹⁰)_(f)X³ _(g)H_(h) wherein: X³ is F, Cl, Br, I, or OR¹⁰,and R¹⁰ are saturated hydrocarbon radicals containing from 1 to 14carbon atoms, which radicals may be the same or different, and, ifdesired, substituted with any substituent which is inert under thereaction conditions employed during polymerization, f is 1 to 3, g is 0to 2, h is 0 or 1, and f+g+h=3. Trialkylaluminum compounds areparticularly preferred, particularly those wherein each of the alkylgroups contains from 1 to 6 carbon atoms, e.g., Al(CH₃)₃, Al(C₂H₅)₃,Al(i-C₄H₉)₃, and Al(C₆H₁₃)₃.

SCA Bounded by no particular theory, it is believed that provision ofone or more SCA (selectivity control agent) in the catalyst compositioncan affect the following properties of the formant polymer: level oftacticity (i.e., xylene soluble material), molecular weight (i.e., meltflow), molecular weight distribution (MWD), melting point, and/oroligomer level. The SCA, also known as external donor or externalelectron donor, used in the invention is typically one of those known inthe art. The SCAs known in the art include, but are not limited to,silicon compounds, esters of carboxylic acids, (especially diesters),monoethers, diethers (e.g., 1,3-dimethoxy propane or 2,2-diisobutyl-1,3dimethoxy propane), and amines (e.g., tetramethylpiperidine).

Preferably, the silicon compounds employed as SCAs contain at least onesilicon-oxygen-carbon linkage. Suitable silicon compounds include thosehaving the formula R¹¹ _(i)SiY_(j)X⁴ _(k) wherein: R¹¹ is a hydrocarbonradical containing from 1 to 20 carbon atoms, Y is —OR¹² or —OCOR¹²wherein R¹² is a hydrocarbon radical containing from 1 to 20 carbonatoms, X⁴ is hydrogen or halogen, i is an integer having a value of from0 to 3, j is an integer having a value of from 1 to 4, k is an integerhaving a value of from 0 to 1, and preferably 0, and i+j+k=4.Preferably, R¹¹ and R¹² are alkyl, aryl or alkaryl ligands of C₁-C₁₀.Each R¹¹ and R¹² may be the same or different, and, if desired,substituted with any substituent which is inert under the reactionconditions employed during polymerization. Preferably, R¹² contains from1 to 10 carbon atoms when it is aliphatic and may be sterically hinderedor cycloaliphatic, and from 6 to 10 carbon atoms when it is aromatic.

Examples of R¹¹ include cyclopentyl, t-butyl, isopropyl, cyclohexyl ormethyl cyclohexyl. Examples of R¹² include methyl, ethyl, butyl,isopropyl, phenyl, benzyl and t-butyl. Examples of X⁴ are Cl and H.Preferred silicon SCAs are alkylalkoxysilanes such asdiethyldiethoxysilane, diphenyl dimethoxy silane,diisobutyldimethoxysilane, cyclohexylmethyldimethoxysilane,n-propyltrimethoxysilane, or dicyclopentyldimethoxysilane.

Silicon compounds in which two or more silicon atoms are linked to eachother by an oxygen atom, i.e., siloxanes or polysiloxanes, may also beemployed, provided the requisite silicon-oxygen-carbon linkage is alsopresent. Other preferred SCAs are esters of aromatic monocarboxylic ordicarboxylic acids, particularly alkyl esters, such as PEEB, DIBP, andmethyl paratoluate.

The SCA is provided in a quantity sufficient to provide from about 0.01mole to about 100 moles per mole of titanium in the procatalyst. It ispreferred that the SCA is provided in a quantity sufficient to providefrom about 0.5 mole to about 70 moles per mole of titanium in theprocatalyst, with about 8 moles to about 50 moles being more preferred.

Nonlimiting examples of suitable silicon compounds for the SCA includethose mentioned in U.S. Pat. No. 7,491,670, WO2009/029486, orWO2009/029487 and any combinations thereof. The SCA can be a mixture ofat least 2 silicon compounds (i.e., a mixed SCA, or mixed externalelectron donor, or “MEED”). A MEED may comprise two or more of any ofthe foregoing SCA compounds. A preferred mixture can bedicyclopentyldimethoxysilane and methylcyclohexyldimethoxysilane,dicyclopentyldimethoxysilane and tetraethoxysilane, ordicyclopentyldimethoxysilane and n-propyltriethoxysilane.

ALA

The catalyst composition may include an activity limiting agent (ALA).As used herein, an “activity limiting agent” (“ALA”) is a material thatreduces catalyst activity at elevated temperature (i.e., temperaturegreater than about 85° C.). An ALA inhibits or otherwise preventspolymerization reactor upset and ensures continuity of thepolymerization process. Typically, the activity of Ziegler-Nattacatalysts increases as the reactor temperature rises. Ziegler-Nattacatalysts also typically maintain high activity near the melting pointtemperature of the polymer produced. The heat generated by theexothermic polymerization reaction may cause polymer particles to formagglomerates and may ultimately lead to disruption of continuity for thepolymer production process. The ALA reduces catalyst activity atelevated temperature, thereby preventing reactor upset, reducing (orpreventing) particle agglomeration, and ensuring continuity of thepolymerization process.

The ALA may or may not be a component of the SCA and/or the MEED. Theactivity limiting agent may be a carboxylic acid ester, a diether, apoly(alkene glycol), a diol ester, and combinations thereof. Thecarboxylic acid ester can be an aliphatic or aromatic, mono- orpoly-carboxylic acid ester. Nonlimiting examples of suitablemonocarboxylic acid esters include ethyl and methyl benzoate, ethylp-methoxybenzoate, methyl p-ethoxybenzoate, ethyl p-ethoxybenzoate,ethyl acrylate, methyl methacrylate, ethyl acetate, ethylp-chlorobenzoate, hexyl p-aminobenzoate, isopropyl naphthenate, n-amyltoluate, ethyl cyclohexanoate and propyl pivalate.

Nonlimiting examples of suitable ALAs include those disclosed inWO2009085649, WO2009029487, WO2009029447, or WO2005030815, andcombinations thereof.

The SCA and/or ALA can be added into the reactor separately.Alternatively, the SCA and the ALA can be mixed together in advance andthen added to the catalyst composition and/or into the reactor as amixture. In the mixture, more than one SCA or more than one ALA can beused. A preferred mixture is dicyclopentyldimethoxysilane and isopropylmyristate, dicyclopentyldimethoxysilane and poly(ethylene glycol)laurate, dicyclopentyldimethoxysilane and isopropyl myristate andpoly(ethylene glycol) dioleate, methylcyclohexyldimethoxysilane andisopropyl myristate, n-propyltrimethoxysilane and isopropyl myristate,dimethyldimethoxysilane and methylcyclohexyldimethoxysilane andisopropyl myristate, dicyclopentyldimethoxysilane andn-propyltriethoxysilane and isopropyl myristate, anddicyclopentyldimethoxysilane and tetraethoxysilane and isopropylmyristate, and combinations thereof.

The catalyst composition may include any of the foregoing SCAs or MEEDsin combination with any of the foregoing activity limiting agents (orALAs).

Preparation of the Catalyst or Catalyst Composition

The components of the olefin polymerization catalyst can be contacted bymixing in a suitable reactor outside the system in which olefin is to bepolymerized and the catalyst thereby produced subsequently is introducedinto the polymerization reactor. The premixed components may be driedafter contact or left in the contact solvent. Alternatively, however,the catalyst components may be introduced separately into thepolymerization reactor. As another alternative, two or more of thecomponents may be mixed partially or completely with each other (e.g.premixing SCA and cocatalyst, or premixing the SCA and ALA) prior tobeing introduced into the polymerization reactor. Another alternative isto contact the supported catalyst component with an organoaluminumcompound prior to reaction with the other catalyst components. Adifferent alternative is to pre-polymerize a small amount of olefin withthe catalyst components or put any of the components on a support (e.g.,silica or a non-reactive polymer).

Polymerization

One or more olefin monomers can be introduced into a polymerizationreactor to react with the catalyst and to form a polymer, or a fluidizedbed of polymer particles. Nonlimiting examples of suitable olefinmonomers include ethylene, propylene, C₄₋₂₀ α-olefins, such as 1-butene,1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene,1-dodecene and the like; C₄₋₂₀ diolefins, such as 1,3-butadiene,1,3-pentadiene, norbornadiene, 5-ethylidene-2-norbornene (ENB), anddicyclopentadiene; C₈₋₄₀ vinyl aromatic compounds including styrene, o-,m-, and p-methylstyrene, divinylbenzene, vinylbiphenyl, vinylnapthalene;and halogen-substituted C₈₋₄₀ vinyl aromatic compounds such aschlorostyrene and fluorostyrene.

As used herein, “polymerization conditions” are temperature and pressureparameters within a polymerization reactor suitable for promotingpolymerization between the catalyst composition and an olefin to formthe desired polymer. The polymerization process may be a gas phase, aslurry, or a bulk polymerization process, operating in one, or more thanone, polymerization reactor. Accordingly, the polymerization reactor maybe a gas phase polymerization reactor, a liquid-phase polymerizationreactor, or a combination thereof.

It is understood that provision of hydrogen in the polymerizationreactor is a component of the polymerization conditions. Duringpolymerization, hydrogen is a chain transfer agent and affects themolecular weight (and correspondingly the melt flow rate) of theresultant polymer.

Polymerization may occur by way of gas phase polymerization. As usedherein, “gas phase polymerization” is the passage of an ascendingfluidizing medium, the fluidizing medium containing one or moremonomers, in the presence of a catalyst through a fluidized bed ofpolymer particles maintained in a fluidized state by the fluidizingmedium. “Fluidization,” “fluidized,” or “fluidizing” is a gas-solidcontacting process in which a bed of finely divided polymer particles islifted and agitated by a rising stream of gas. Fluidization occurs in abed of particulates when an upward flow of fluid through the intersticesof the bed of particles attains a pressure differential and frictionalresistance increment exceeding particulate weight. Thus, a “fluidizedbed” is a plurality of polymer particles suspended in a fluidized stateby a stream of a fluidizing medium. A “fluidizing medium” is one or moreolefin gases, optionally a carrier gas (such as H₂ or N₂) and optionallya liquid (such as a hydrocarbon) which ascends through the gas-phasereactor.

A typical gas-phase polymerization reactor (or gas phase reactor)includes a vessel (i.e., the reactor), the fluidized bed, a distributionplate, inlet and outlet piping, a compressor, a cycle gas cooler or heatexchanger, and a product discharge system. The vessel includes areaction zone and a velocity reduction zone, each of which is locatedabove the distribution plate. The bed is located in the reaction zone.In an embodiment, the fluidizing medium includes propylene gas and atleast one other gas such as an olefin and/or a carrier gas such ashydrogen or nitrogen.

Contacting of the catalyst and the olefin occurs by way of feeding thecatalyst composition into a polymerization reactor and introducing theolefin into the polymerization reactor. The cocatalyst can be mixed withthe supported catalyst component (pre-mix) prior to the introduction ofthe supported catalyst component into the polymerization reactor. Thecocatalyst may also be added to the polymerization reactor independentlyof the supported catalyst component. The independent introduction of thecocatalyst into the polymerization reactor can occur simultaneously, orsubstantially simultaneously, with the supported catalyst componentfeed.

The polymerization process may include a pre-polymerization step.Pre-polymerization includes contacting a small amount of the olefin withthe procatalyst composition after the supported catalyst component hasbeen contacted with the co-catalyst and the SCA and/or the activitylimiting agent. Then, the resulting preactivated catalyst stream isintroduced into the polymerization reaction zone and contacted with theremainder of the olefin monomer to be polymerized, and optionally one ormore of the SCA components and/or activity limiting agent components.Pre-polymerization results in the supported catalyst component beingcombined with the cocatalyst and the SCA and/or the activity limitingagent, the combination being dispersed in a matrix of the formantpolymer. Optionally, additional quantities of the SCA and/or theactivity limiting agent may be added.

The polymerization process may include a pre-activation step.Pre-activation includes contacting the supported catalyst component withthe co-catalyst and the SCA and/or the activity limiting agent. Theresulting preactivated catalyst stream is subsequently introduced intothe polymerization reaction zone and contacted with the olefin monomerto be polymerized, and optionally one or more of the SCA components.Pre-activation results in the supported catalyst component beingcombined with the cocatalyst and the SCA and/or the activity limitingagent. Optionally, additional quantities of the SCA and/or the activitylimiting agent may be added.

The process may include mixing the SCA (and optionally the activitylimiting agent) with the supported catalyst component. The SCA can becomplexed with the cocatalyst and mixed with the supported catalystcomponent (pre-mix) prior to contact between the catalyst compositionand the olefin. The SCA and/or the activity limiting agent can be addedindependently to the polymerization reactor. Preferred SCAs includedicyclopentyldimethoxysilane or n-propyltrimethoxysilane.

A preferred catalyst composition includes an SCA such asdicyclopentyldimethoxysilane and/or n-propyltrimethoxysilane and/ormethylcyclohexyldimethoxysilane, and an activity limiting agent such asisopropyl myristate.

The olefin may be propylene wherein the process includes forming apropylene-based polymer having a melt flow rate (MFR) from about 0.01g/10 min to about 800 g/10 min, or from about 0.1 g/10 min to about 200g/10 min, or from about 0.5 g/10 min to about 150 g/10 min. Further, thepropylene-based polymer is a polypropylene homopolymer.

The olefin may be propylene wherein the process includes forming apropylene-based polymer having a xylene solubles content from about 0.5%to about 10%, or from about 1% to about 8%, or from about 1% to about4%. Further, the propylene-based polymer is a polypropylene homopolymer.

The present disclosure provides another process for producing anolefin-based polymer. The olefin may be propylene and a mixture of atleast one other suitable olefin comonomer wherein the process includesforming a propylene-based interpolymer. The preferred comonomer isethylene and/or 1-butene and the formant interpolymer has a melt flowrate (MFR) from about 0.01 g/10 min to about 200 g/10 min, or from about0.1 g/10 min to about 100 g/10 min, or from about 0.5 g/10 min to about70 g/10 min. Further, the preferred propylene-based interpolymer is arandom copolymer.

The olefin may be propylene and a mixture of at least one other suitableolefin comonomer wherein the process includes forming a propylene-basedinterpolymer. The preferred comonomer is ethylene and/or 1-butene andthe formant interpolymer has a xylene solubles content from about 0.5%to about 40%, or from about 1% to about 30%, or from about 1% to about20%. Further, the preferred propylene-based interpolymer is a randomcopolymer.

The olefin may be propylene and a mixture of at least one other suitableolefin comonomer wherein the process includes forming a propylene-basedinterpolymer. The preferred comonomer is ethylene and/or 1-butene andthe formant interpolymer has a weight percent comonomer content relativeto propylene of from about 0.001% to about 20%, or from about 0.01% toabout 15%, or from about 0.1% to about 10%. Further, the preferredpropylene-based interpolymer is a random copolymer.

The present disclosure provides another process for producing anolefin-based polymer. A process for producing an olefin-based polymer isprovided which includes contacting propylene with a catalyst compositioncomprising a dicarbonate to form a propylene-based polymer. The contactbetween the propylene and the catalyst composition occurs in a firstpolymerization reaction under polymerization conditions. The processfurther includes contacting ethylene and optionally at least one otherolefin in the presence of the propylene-based polymer. The contactbetween the ethylene, the olefin(s), and the propylene-based polymeroccurs in a second polymerization reactor under polymerizationconditions and forms a propylene impact copolymer.

The first reactor and the second reactor may operate in series wherebythe effluent of the first reactor (i.e., the propylene-based polymer) ischarged to the second reactor. Additional olefin monomer is added to thesecond polymerization reactor to continue polymerization. Additionalcatalyst composition (and/or any combination of individual catalystcomponents—i.e., supported catalyst component, cocatalyst, EED or MEED,ALA) may be added to the second polymerization reactor. The additionalcatalyst composition/components added to the second reactor may be thesame or different than the catalyst composition/components introduced inthe first reactor.

The propylene-based polymer produced in the first reactor is a propylenehomopolymer. The propylene homopolymer is charged to the second reactorwhere ethylene and propylene are contacted with each other in thepresence of the propylene homopolymer. This forms a propylene impactcopolymer having a propylene homopolymer continuous (or matrix) phaseand a discontinuous phase (or rubber phase) selected from apropylene-based copolymer (i.e., a propylene/ethylene copolymer) or anethylene-based copolymer (i.e., an ethylene/propylene copolymer). Thediscontinuous phase is dispersed in the continuous phase.

The propylene impact copolymer may have an Fc value from about 1 wt % toabout 50 wt %, or from about 10 wt % to about 40 wt %, or from about 20wt % to about 30 wt %. As used herein, “fraction copolymer” (“Fc”) isthe weight percent of the discontinuous phase present in theheterophasic copolymer. The Fc value is based on the total weight of thepropylene impact copolymer.

The propylene impact copolymer may have an Ec value from about 1 wt % toabout 100 wt %, or from about 20 wt % to about 90 wt %, or from about 30wt % to about 80 wt %, or from about 40 wt % about 60 wt %. As usedherein, “ethylene content” (“Ec”) is the weight percent of ethylenepresent in the discontinuous phase of the propylene impact copolymer.The Ec value is based on the total weight of the discontinuous (orrubber) phase.

Test Methods

Polydispersity Index (PDI) is measured by an AR-G2 rheometer which is astress control dynamic spectrometer manufactured by TA Instruments usinga method according to Zeichner G. R., Patel P. D. (1981) “Acomprehensive Study of Polypropylene Melt Rheology” Proc. of the 2ndWorld Congress of Chemical Eng., Montreal, Canada. An ETC oven is usedto control the temperature at 180° C.±0.1° C. Plant nitrogen purgedinside the oven to keep sample from degradation by oxygen and moisture.A pair of 25 mm in diameter cone and plate sample holder is used.Samples are compress molded into 50 mm×100 mm×2 mm plaque. Samples arecut into 19 mm square and loaded on the center of the bottom plate. Thegeometries of upper cone is (1) Cone angle: 5:42:20 (deg:min:sec); (2)Diameter: 25 mm; (3) Truncation gap: 149 micron. The geometry of thebottom plate is 25 mm cylinder. Testing procedure:

-   -   (i) The cone & plate sample holder are heated in the ETC oven at        180° C. for 2 hours. Then the gap is zeroed under blanket of        nitrogen gas.    -   (ii) Cone is raised to 2.5 mm and sample loaded unto the top of        the bottom plate.    -   (iii) Start timing for 2 minutes.    -   (iv) The upper cone is immediately lowered to slightly rest on        top of the sample by observing the normal force.    -   (v) After two minutes the sample is squeezed down to 165 micron        gap by lower the upper cone.    -   (vi) The normal force is observed when the normal force down to        <0.05 Newton the excess sample is removed from the edge of the        cone and plate sample holder by a spatula.    -   (vii) The upper cone is lowered again to the truncation gap        which is 149 micron.    -   (viii) An Oscillatory Frequency Sweep test is performed under        these conditions:        -   Test delayed at 180° C. for 5 minutes.        -   Frequencies: 628.3 r/s to 0.1 r/s.        -   Data acquisition rate: 5 point/decade.        -   Strain: 10%    -   (ix) When the test is completed the crossover modulus (Gc) is        detected by the Rheology Advantage Data Analysis program        furnished by TA Instruments.    -   (x) PDI=100,000÷Gc (in Pa units).

Melt flow rate (MFR) or “Melt flow” is measured in accordance with ASTMD 1238-01 test method at 230° C. with a 2.16 kg weight forpropylene-based polymers.

Xylene Solubles (XS) is measured according to the following procedure. Atotal of 0.4 g of polymer is dissolved in 20 ml of xylenes with stirringat 130° C. for 30 minutes. The solution is then cooled to 25° C., andafter 30 minutes the insoluble polymer fraction is filtered off. Theresulting filtrate is analyzed by Flow Injection Polymer Analysis usinga Viscotek ViscoGEL H-100-3078 column with THF mobile phase flowing at1.0 ml/min. The column is coupled to a Viscotek Model 302 TripleDetector Array, with light scattering, viscometer and refractometerdetectors operating at 45° C. Instrument calibration was maintained withViscotek PolyCAL™ polystyrene standards.

Final melting point, T_(MF) or (“TMF”), is the temperature to melt themost perfect crystal in the sample and is regarded as a measure forisotacticity and inherent polymer crystallizability. The test isconducted using a TA Q100 Differential Scanning calorimeter. A sample isheated from 0° C. to 240° C. at a rate of 80° C./min, cooled at the samerate to 0° C., then heated again at the same rate up to 150° C., held at150° C. for 5 minutes and the heated from 150° C. to 180° C. at 1.25°C./min. The T_(MF) is determined from this last cycle by calculating theonset of the baseline at the end of the heating curve. Testing Procedurefor TMF:

-   -   ((1) Calibrate instrument with high purity indium as standard.    -   (2) Purge the instrument head/cell with a constant 50 ml/min        flow rate of nitrogen constantly.    -   (3) Sample preparation: Compression mold 1.5 g of powder sample        using a 30-G302H-18-CX Wabash Compression Molder (30 ton): (a)        heat mixture at 230° C. for 2 minutes at contact; (b) compress        the sample at the same temperature with 20 ton pressure for 1        minute; (c) cool the sample to 45° F. and hold for 2 minutes        with 20 ton pressure; (d) cut the plaque into 4 of about the        same size, stack them together, and repeat steps (a)-(c) in        order to homogenize sample.    -   (4) Weigh a piece of sample (preferably between 5 to 8 mg) from        the sample plaque and seal it in a standard aluminum sample pan.        Place the sealed pan containing the sample on the sample side of        the instrument head/cell and place an empty sealed pan in the        reference side. If using the auto sampler, weigh out several        different sample specimens and set up the machine for a        sequence.    -   (5) Measurements:        -   (i) Data storage: off        -   (ii) Ramp 80.00° C./min to 240.00° C.        -   (iii) Isothermal for 1.00 min        -   (iv) Ramp 80.00° C./min to 0.00° C.        -   (v) Isothermal for 1.00 min        -   (vi) Ramp 80.00° C./min to 150.00° C.        -   (vii) Isothermal for 5.00 min        -   (viii) Data storage: on        -   (ix) Ramp 1.25° C./min to 180.00° C.        -   (x) End of method    -   (6) Calculation: T_(MF) is determined by the interception of two        lines. Draw one line from the base-line of high temperature.        Draw another line from through the deflection of the curve close        to the end of the curve at high temperature side.

The following Examples are meant to help illustrate the presentinvention but are not intended to limit the scope of the invention asdefined by the claims.

EXAMPLES

General preparation for the preparation of5-tert-butyl-3-methyl-1,2-phenylene diethyl dicarbonate (ID-1),5-tert-butyl-3-methyl-1,2-phenylene diphenyl dicarbonate (ID-2), and3,5-diisopropyl-1,2-phenylene diethyl dicarbonate (ID-3): To around-bottom flask was charged the appropriate catechol (30 mmol),pyridine (4.8 g, 60 mmol, 2.0 equiv.), and anhydrous methylene chloride(60 ml). The flask was immersed in an ice-water bath, and theappropriate chloroformate (60 mmol, 2.0 equiv.) was added dropwise. Themixture was raised to room temperature and stirred overnight. Theprecipitate was filtered off and washed with additional methylenechloride. The combined filtrate was washed with water, saturated NH₄Clor 1N HCl solutions (aqueous), water, saturated sodium bicarbonate, andbrine consequently, and dried over magnesium sulfate. After filtration,the filtrate was concentrated, and the residue was purified byrecrystallization or by flash column chromatography on silica gel.

5-tert-butyl-3-methyl-1,2-phenylene diethyl dicarbonate (ID-1): Preparedfrom 5-tert-butyl-3-methylbenzene-1,2-diol and ethyl chloroformate;purified by flash column chromatography on silica gel to yield a stickycolorless oil (81.4%); ¹H NMR (500 MHz, CDCl₃, ppm) δ 7.09-7.11 (m, 2H),4.32 (q, 2H, J=9.0 Hz), 4.31 (q, 2H, J=9.0 Hz), 2.25 (s, 3H), 1.38 (t,3H, J=9.0 Hz), 1.37 (t, 3H, J=9.0 Hz), 1.29 (s, 9H);

5-tert-butyl-3-methyl-1,2-phenylene diphenyl dicarbonate (ID-2):Prepared from 5-tert-butyl-3-methylbenzene-1,2-diol and phenylchloroformate; purified by recrystallization from ethanol to yield awhile solid (75.2%); ¹H NMR (500 MHz, CDCl₃, ppm): δ 7.35-7.38 (m, 4H),7.23-7.28 (m, 7H), 7.16-7.17 (m, 1H), 2.36 (s, 3H), 1.32 (s, 9H).

3,5-diisopropyl-1,2-phenylene diethyl dicarbonate (ID-3): Prepared from3,5-diisopropylbenzene-1,2-diol and ethyl chloroformate; purified byflash column chromatography on silica gel to yield a yellow oil (59.1%);¹H NMR (500 MHz, CDCl₃, ppm) δ 7.02 (s, 1H), 6.98 (s, 1H), 4.32 (q, 2H,J=7.0 Hz), 4.31 (q, 2H, J=7.0 Hz), 3.11 (heptat, 1H, J=7.3 Hz), 2.89(heptat, 1H, J=7.0 Hz), 1.38 (t, 3H, J=7.3 Hz), 1.37 (t, 3H, J=7.0 Hz),1.24 (d, 6H, J=7.0 Hz), 1.22 (d, 6H, J=7.5 Hz).

Structures of the internal donors which were obtained commercially(diisobutyl phthalate and diethyl carbonate), or prepared as describedherein, are shown in Table 1.

TABLE 1 Structure of the Internal Donors used in Examples: Chemical NameDonor Identity Structure diisobutyl phthalate (CAS # 84-69-5) DIBP(comparative)

diethyl carbonate (CAS # 105-58-8) DEC (comparative)

5-tert-butyl-3-methyl-1,2- phenylene diethyl dicarbonate ID-1

5-tert-butyl-3-methyl-1,2- phenylene diphenyl dicarbonate ID-2

3,5-diisopropyl-1,2-phenylene diethyl dicarbonate ID-3

Preparation of Supported Catalyst Components

Under nitrogen, 3.0 g of MagTi (mixed magnesium/titanium halidealcoholate; CAS #173994-66-6, see U.S. Pat. No. 5,077,357), the amountof internal electron donor indicated in Table 2 below, and 60 mL of a50/50 (vol/vol) mixture of titanium tetrachloride and chlorobenzene ischarged to a vessel equipped with an integral filter. After heating to115° C. for 60 minutes with stirring, the mixture is filtered. Thesolids are treated with an additional 60 mL of fresh 50/50 (vol/vol)mixed titanium tetrachloride/chlorobenzene, and optionally (as indicatedin table 2 below), a second charge of internal electron donor, at 115°C. for 30 minutes with stirring. The mixture is filtered. The solids areagain treated with 60 mL of fresh 50/50 (vol/vol) mixed titaniumtetrachloride/chlorobenzene at 115° C. for 30 minutes with stirring. Themixture is filtered. At ambient temperature, the solids are washed threetimes with 70 mL of isooctane, then dried under a stream of nitrogen.The solid catalyst components are collected as powders and a portion ismixed with mineral oil to produce a 5.4 wt % slurry. The identity ofinternal electron donor used, their amounts, and timing of addition aredetailed below (Table 2).

TABLE 2 Amounts of Internal Donors Used for Supported CatalystComponents Solid Catalyst Internal mmol donor mmol donor DesignationElectron Donor (1st hot addition) (2nd hot addition) Comp 1a DIBP 2.420.0 Comp 1b DIBP 2.42 0.0 Comp 2 DEC 2.42 0.0 Cat 1-1 ID-1 2.42 0.0 Cat1-2 ID-1 2.42 2.42 Cat 2 ID-2 2.42 0.00 Cat 3 ID-3 2.42 0.0

Generation of Active Polymerization Catalyst

In an inert atmosphere glovebox the active catalyst mixture is preparedby premixing the quantities indicated in Tables 3-4 of external donor(if present), triethylaluminum (as a 0.28 M solution), supportedcatalyst component (as a 5.4% mineral oil slurry), and 5-10 mL isooctanediluent (optional) for 20 minutes. After preparation, and withoutexposure to air, the active catalyst mixture is injected into thepolymerization reactor as described below.

Batch Reactor Propylene Polymerization (Homopolymer):

Polymerizations are conducted in a stirred, 3.8 L stainless steelautoclave.

Temperature control is maintained by heating or cooling an integratedreactor jacket using circulated water. The top of the reactor isunbolted after each run so that the contents can be emptied afterventing the volatiles. All chemicals used for polymerization or catalystpreparation are run through purification columns to remove impurities.Propylene and solvents are passed through 2 columns, the firstcontaining alumina, the second containing a purifying reactant (Q5™available from Engelhard Corporation). Nitrogen and hydrogen gases arepassed through a single column containing Q5™ reactant.

After attaching the reactor head to the body, the reactor is purged withnitrogen while being heated to 140° C. and then while cooling toapproximately 30° C. The reactor is then filled with a solution ofdiethylaluminum chloride in isooctane (1 wt %) and agitated for 15minutes. This scavenging solution is then flushed to a recovery tank andthe reactor is filled with ˜1375 g of propylene. The appropriate amountof hydrogen is added using a mass flow meter (see Tables 3-4) and thereactor is brought to 62° C. The active catalyst mixture is injected asa slurry in oil or light hydrocarbon and the injector is flushed withisooctane three times to ensure complete delivery. After injection ofcatalyst, the reactor temperature is ramped to 67° C. over 5 minutes, ormaintained at 67° C. via cooling in the case of large exotherms. After arun time of 1 hour, the reactor is cooled to ambient temperature,vented, and the contents are emptied. Polymer weights are measured afterdrying overnight or to constant weight in a ventilated fume hood.

TABLE 3 Polymerization Results at 0.41 mol % (H₂/C₃) Conditions: 200 mgcatalyst slurry; 0.15 mmol external donor; 1.5 mmol Al Example SolidCatalyst Internal External Yield Melt Flow TMF Eff (kg # DesignationDonor Donor PP (g) (g/10 min) XS (° C.) PDI PP/g cat) 1c Comp 1a* DIBPNPTMS 258 21.8 2.8 169.9 4.08 24 2c Comp 2* DEC NPTMS 180 48.9 10.9 — —17 3  Cat 1-1 ID-1 NPTMS 146 16.5 2.3 169.9 4.40 14 4  Cat 1-2 ID-1NPTMS 184 20.7 2.2 170.9 3.88 17 5c Comp 1a* DIBP DCPDMS 341 7.5 2.9171.7 4.69 32 6c Comp 2* DEC DCPDMS 367 35.0 11.4 — — 34 7  Cat 1-1 ID-1DCPDMS 326 14.0 2.6 170.1 4.80 31 8  Cat 1-2 ID-1 DCPDMS 389 21.1 3.6170.8 4.84 36 9  Cat 2 ID-2 DCPDMS 438 9.8 5.5 169.9 4.61 41 10  Cat 3ID-3 DCPDMS 392 21.9 3.4 — — 37 *= comparative; not an example of theinvention “—” = not determinedAnalysis of the data in Table 3 reveals the following:

-   A. The XS of polymer from catalysts employing any of the inventive    dicarbonate donors is much lower than when using the monocarbonate    comparative catalyst (Comp 2).-   B. When using NPTMS as an external donor, the TMF of polymer from    the catalyst employing inventive donor (ID-1; Cat 1-2) is higher    than when using the comparative catalyst (Comp 1a).-   C. When using NPTMS as an external donor, the XS of polymer from    both catalysts employing inventive donors (ID-1) is lower than when    using the comparative catalyst (Comp 1a or Comp 2).-   D. When using DCPDMS as an external donor, the MF of polymer from    catalysts employing any of the inventive donors is higher than when    using the comparative catalyst (Comp 1a).-   E. Efficiency of the inventive catalysts is strong (>14 kg PP/g    catalyst).-   F. Efficiency of the inventive catalyst employing inventive donor    (ID-2 or ID-3) is higher than when using the comparative catalysts    (Comp 1a or Comp 2).

TABLE 4 Polymerization Results at 0.82 mol % (H₂/C₃) Conditions: 200 mgcatalyst slurry; 0.15 mmol external donor; 1.5 mmol Al Example SolidCatalyst Internal External Yield Melt Flow TMF Eff (kg # DesignationDonor Donor PP (g) (g/10 min) XS (° C.) PDI PP/g cat)  11c Comp 1b* DIBPDCPDMS 447 19.7 2.7 171.3 4.94 42 12 Cat 1-1 ID-1 DCPDMS 322 87.3 2.7170.8 4.09 30 13 Cat 1-2 ID-1 DCPDMS 308 86.6 2.3 170.4 hmf 29 *=comparative; not an example of the invention hmf = polymer is “high meltflow” and yields a PDI measurement which must be extrapolatedAnalysis of the data in Table 4 reveals the following:

-   A. The XS of polymer from the catalyst employing inventive donor    (ID-1; Cat 1-2) is lower than when using the comparative catalyst.-   B. The PDI of polymer from catalysts employing inventive donor    (ID-1) is narrower than when using the comparative catalyst.-   C. The MF increase of polymer from catalysts employing any of the    inventive donors is substantial relative to when the comparative    catalyst is used. Therefore, higher MF polymer resin can be made    without cracking.-   D. Efficiency of the inventive catalysts is very strong (>29 kg PP/g    catalyst).

What is claimed is:
 1. A compound suitable for use as an internalelectron donor having a structure:

wherein R₁ is independently at each occurrence, an aliphatic or aromatichydrocarbon, or substituted hydrocarbon group containing from 1 to 20carbon atoms; R₂ is independently at each occurrence, a hydrogen atom oraliphatic or aromatic hydrocarbon, or substituted hydrocarbon groupcontaining from 1 to 20 carbon atoms; and R3 is an aliphatic hydrocarbylgroup having 1 to 3 carbon atoms.
 2. The compound of claim 1 wherein R1is independently at each occurrence, an aliphatic or aromatichydrocarbon group containing from 1 to 6 carbon atoms; and R2 isindependently at each occurrence, a hydrogen atom or aliphatic oraromatic hydrocarbon group containing from 1 to 6 carbon atoms; and R3is an aliphatic hydrocarbyl group having 1 to 3 carbon atoms.
 3. Thecompound of claim 1 wherein R1 is independently at each occurrence, amethyl, ethyl, isopropyl, t-butyl, or phenyl group; and R2 isindependently at each occurrence, a hydrogen atom or a methyl, ethyl, orisopropyl group; and R3 is a methyl, ethyl, or isopropyl group.
 4. Thecompound of claim 1 wherein R1 is independently at each occurrence, anethyl, isopropyl, t-butyl, or phenyl group; and R2 is independently ateach occurrence, a hydrogen atom; and R3 is a methyl or isopropyl group.